21212211221989 has 2 divisors, whose sum is σ = 21212211221990. Its totient is φ = 21212211221988.

The previous prime is 21212211221969. The next prime is 21212211222043. The reversal of 21212211221989 is 98912211221212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17139947761764 + 4072263460225 = 4140042^2 + 2017985^2 .

It is a cyclic number.

It is not a de Polignac number, because 21212211221989 - 2¹⁹ = 21212210697701 is a prime.

It is a super-2 number, since 2×21212211221989² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21212211221939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10606105610994 + 10606105610995.

It is an arithmetic number, because the mean of its divisors is an integer number (10606105610995).

Almost surely, 2^{21212211221989} is an apocalyptic number.

It is an amenable number.

21212211221989 is a deficient number, since it is larger than the sum of its proper divisors (1).

21212211221989 is an equidigital number, since it uses as much as digits as its factorization.

21212211221989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 41472, while the sum is 43.

The spelling of 21212211221989 in words is "twenty-one trillion, two hundred twelve billion, two hundred eleven million, two hundred twenty-one thousand, nine hundred eighty-nine".